Princess Diana always leaned on Prince Philip to help her with her difficult royal life

Princess Diana had always sought solace in her father-in-law Prince Philip's company during her days of struggle within the British royal family.

Details of their bond were shared by royal author Ingrid Sewart in her new book, Prince Philip Revealed who gave an insight the Duke of Edinburgh and the Princess of Wales' strong yet rocky relationship.

In an excerpt published in the first issue of PEOPLE Royals, she wrote: "When (Diana) found the restrictions of royal life difficult, it was Philip who helped her.”

"Once she was married, she never sat next to her husband; she was always sat next to Philip at the endless black-tie dinners, and he took care of her,” Seward wrote further.

"Diana found the Balmoral dinners a massive strain and the atmosphere stifling. When the piper came around the table after dinner with his kilt swirling and his pipes whining, she couldn't wait to leave the room."

Philip and Diana remained close even after Andrew Morton published his bombshell book in 1992, titled Diana: Her True Story, spilling secrets to the People’s Princess’ struggles in her marriage to Prince Charles.

The author says that following the publication, Queen Elizabeth II had arranged a family meeting with Charles and Diana to let them sort out their issues.

During the meeting, Philip asked the young couple to "try to think of their children, the monarchy and the country instead of their personal woes.”

“He tried to make her face facts and deal with the problems within her marriage, explaining he knew first-hand the difficulties of marrying into the royal family," said Seward.

Writing some of the several letters sent to his daughter-in-law, Philip signed them as “Pa” and expressed his sympathies with Diana as his son got involved in an extramarital affair with his ex-girlfriend Camilla Parker Bowles.

"We never dreamed that he might feel like leaving you for her. I cannot imagine anyone in their right mind leaving you for Camilla. Such a prospect never entered our heads,” wrote Philip in one of the letters.

In another note, the Duke told Diana: "If invited, I will always do my utmost to help you and Charles to the best of my ability. But I am quite ready to concede that I have no talent as a marriage counselor.”